A cellular communications network typically comprises a plurality of individual cells. A cell is typically controlled by a base station, which may be connected to a backbone network by a wire-line connection. The backbone network may connect base stations to each other, to base station controllers or to core network nodes. Base stations communicate with mobile stations within cell coverage areas of their cells using a wireless radio interface. A base station may control more than one cell.
A mobile may change attachment from a first cell to a second cell as it moves around in the overall coverage area of the cellular communication system. A change in attachment may be referred to as a handover or handoff. In handover, a mobile may be handed over from a source base station to a target base station. A handover may be initiated responsive to a measurement report being received from a mobile in a base station, the measurement report indicating that radio conditions at the mobile have changed so that another cell, which will become the target cell for the handover, has become more suitable for radio communication with the mobile.
Mobiles may prefer different treatment from the network, for example, a mobile may prefer to use a certain version of a speech codec, a certain kind of pattern of discontinuous reception, DRX, or other parameter that is not mandated by the network to be set to a certain value. During handover, a source base station may inform the target base station of preferences expressed by the mobile, so the target base station becomes capable, to an extent, of anticipating the mobiles behavior.